The present invention relates to a machine tool that continuously removes chips by means of air suction during processing a work.
FIG. 4 shows a machine tool of Japanese Patent No. 2827003 by this inventors. As shown in this figure, there has been a chip suction machine tool having a tool attaching part 200 and a spindle head 100. The tool attaching part 200 includes a vent hole s1 for discharging chips and air through a hood means 13 surrounding a cutting tool 11. The spindle head 100, on which the tool attaching part 200 is mounted, has an air suction hole s2 that communicates with the vent hole s1.
This kind of machine tool employs simple structures for installing and removing the tool attaching part 200. For example, a downstream end part of the vent hole s1 and an upstream end part of the air suction hole s2 are connected with each other beside a tip end of a spindle 3. In addition, the downstream end part is firmly pressed and connected to the upstream end part on a face fa0 which is perpendicular to the spindle 3.
Though the above machine tool is very useful, the present invention further improve the following problems.
In a conventional machine tool, it is hard to install the tool attaching part 200 on the spindle head 100 or remove it therefrom smoothly and correctly owing to contact pressure working between the downstream end part of the vent hole s1 and the upstream end part of the air suction hole s2.
Besides, when the tool attaching part 200 is installed on the spindle head 100, chips occasionally enter between the downstream end part of the vent hole s1 and the upstream end part of the air suction hole s2. Unless the chips are carefully removed, it is feared that their complete coupling is spoiled by the chips.
Moreover, in order to achieve a firm connection between the downstream end part of the vent hole s1 and the upstream end part of the air suction hole s2, these end parts must be very accurately processed so that their relative positions may meet with each other at a specified position, respectively. This process takes a great deal of time.
Furthermore, the hood means 13 protrudes toward a perpendicular direction to the spindle 3 owing to an existence of the vent hole s1, thereby enlarging and unbalancing the whole body. Besides, its handling is inconvenient.
In addition, especially when using the spindle 3 horizontally, a protruding direction of the tool attaching part 200 becomes incorrect owing to weight of the tool attaching part 200 as well as contact pressure between the downstream end part of the vent hole s1 and the upstream end part of the air suction hole s2, therefore it is feared of having a bad influence on accuracy.
A chip suction type machine tool of this invention comprises a tool attaching part having a vent hole for discharging chips and air through the inside of a hood means that surrounds a cutting tool, and a spindle head having an air suction hole that communicates with the air vent hole. The tool attaching part is installed on the spindle head. The downstream end part of the vent hole is closely faced to the upstream end part of the air suction hole with the tool attaching part installed on the spindle head. A telescoping cylinder means is provided between the downstream and upstream end parts, being extendable or retractable at least one of the end parts. While the telescoping cylinder means is free, it is kept in shrinking by means of an elastic member so as to separate the downstream end part from the upstream end part. When negative pressure is given to the air suction hole with the tool attaching part installed on the spindle, the telescoping cylinder means is extended on the negative pressure, and functions so as to closely connect the downstream end part with the upstream end part.
Here, the telescoping cylinder means, for example as shown in claim 4, comprises a retractable multiple cylinder structural member and an elastic member for shrinking them.
In this invention, when the tool attaching part is installed on or removed from the spindle head, the telescoping cylinder means can keep the downstream end part of the vent hole off the upstream end part of the air suction hole. Therefore, there arises no unbalanced force due to their contact, thereby effecting a smooth and exact treatment.
Besides, when the negative pressure is given to the air suction hole after the tool attaching part is installed on the spindle head, the air is sucked into the air suction hole not only from the inside of the hood means but also from a space between the downstream end part of the vent hole and the upstream end part of the air suction hole. Accordingly, even through chips adhere to the space, they are sucked and carried away with the air without being caught between the downstream end part and the upstream end part.
Moreover, ,while the tool attaching part being installed on the spindle head, the downstream end part of the vent hole is connected with the upstream end part of the air suction hole by an extension work of the telescoping cylinder means. Therefore, even if relatively large error due to manufactural accuracy happens to a relative position of the downstream end part, it cause no trouble in its function.
Furthermore, the downstream end part of the vent hole is closely faced to the upstream end part of the air suction hole so that they may cross to the spindle at a suitable angle xcex8. Therefore, the size of protrusion of the tool attaching part can be downsized.
The above invention can be materialized as the following.
As shown in claim 2, the hood means comprises a hood body surrounding the cutting tool and a cylinder having an opening for receiving a cutting tool on its front end face. The cylinder is retractable in a direction of the cutting tool, and pushed forward in the direction of the cutting tool by means of an elastic member. While the cutting tool is processing the work, the front end face of the cylinder is in contact with a work. Chips produced by the cutting tool join up with air flowing into the cylinder to be discharged outside through the hood body, the vent hole, and the air suction hole.
As shown in claim 3, the hood means comprises a hood body surrounding the cutting tool and a cylinder whose front end face is in a U-letter shape from a cross section view, having a comparatively small opening for receiving the cutting tool at the center. The cylinder is retractable in a direction of the cutting tool, and pushed forward in the direction of the cutting tool by means of an elastic member. Besides, while the cutting tool is processing the work, the front end face of the cylinder is close to but not in contact with a work by air flow caused by the negative pressure of the air suction hole. Chips produced by the cutting tool join up with air flowing into the cylinder and discharged outside through the hood body, the vent hole, and the air suction hole.
As shown in claim 5, the upstream end part of the air suction hole of the spindle head is close connected to the downstream end part of the vent hole of the tool attaching part beside the hood means. Therefore, in spite of the existence of the vent hole, the hood means do not protrude toward the perpendicular direction to the spindle, thereby miniaturizing and balancing the whole body. Besides, when the tool attaching part is used sideways, it does not bend largely due to self weight.
As shown in claim 6, a contact surface of the upstream end part of tile air suction hole of the spindle head and the downstream end part of the vent hole of the tool attaching part is inclined along the direction of the spindle. Here, the contact surface is apart from a rotatory center of the spindle as it goes forward to the spindle. Therefore, miniaturizing the tool attaching part is helped. Besides, when the tool attaching part is installed on or removed from the spindle, the inclination of the contact surface prevents the downstream end part of the vent hole from being caught in the upstream end part of the air suction hole.